The National Institute on Aging (NIA) has funded three sites to conduct studies on the effects of calorie restricted (CR) diets on the aging process. This research program is called the "Comprehensive Assessment of Long-Term Effects of Reducing Intake of Energy" (or, CALERIE). It involves exploratory controlled human intervention studies on the effects of CR on physiology, body composition, and risk factors for age-related pathologies. The primary goals of CALERIE are: to gain knowledge about the effects of sustained CR on physiology, metabolism, body composition, risk factors for age-related pathologies and potential adverse effects; and, to gain knowledge of similarities, differences and interactions between CR and physical activity on the above outcomes. Study populations in the CALERIE studies will be non-obese individuals, with a likely age range of 25-60 years. The outcome measures include energy intake and expenditure, physical activity, body composition, endocrine responses, insulin sensitivity/glucose metabolism, cardiovascuIar function, bone density, immune function, quality of life and potential adverse effects of caloric restriction. The Duke Clinical Research Institute proposes to serve as the Coordinating Center for this project. In this role, we will attend to the following functions. (1) Study Coordination and Planning: We will help establish an efficient organizational structure to ensure that all activities advance in a coordinated fashion. (2) Site Management and Monitoring: We will develop a site management and monitoring plan that educates site staff regarding the conduct of clinical studies, provides training on the Protocol, and improves the quality of the data being collected. (3) Data Management Activities: We will apply sophisticated, multi-dimensional system for on-going data collection and generate periodic reports summarizing the execution of the trial. (3) Statistical Analysis: We will provide statistical leadership in the design of these studies; and perform interim and final analyses in an expeditious and timely manner.